The Saraswati river is said to have flowed independently in the pre-historic region of present day Allahabad – where at a certain point in its flow, it is said to have briefly met & mingled with the waters of Ganga and Yamuna – which still remains as the confluence point known in present day as Triveni Sangam in Allahabad.

EXCEPT, that today, the waters of Saraswati spurt into the Sangam from an underwater source. The Sangam in Allahabad, is perhaps the only point today, in the course of original Saraswati, where is makes a brief upward, visible appearance.

SN Sadasivan in his book, "A Social History of India" on page 236 states:

While some Vedic scholars have identified the river Saraswati with Indus, some others have maintained that it was only a tributary of the Indus, like Satudri (Satluj) as mentioned in hymn 755 of Book X of the Rig Veda. In fact, the river never existed except by a mistaken identity arising from the limited geographic knowledge of the Vedic composers. If so, it will be more appropriate to relate the claim with Saraswati as the new Goddess of learning and not with the river of the same name. Far from their induced belief that they had their first abode on the bank of Saraswati, it is their demand to be associated with the Goddess of learning that indubitably enabled them to establish their eligibility for admission to the priestly class. Recent findings by some geo-scientists based on study of Landsat imageries, lead to the conclusion that the "migratory" river Saraswati is buried ten thousand years ago by fluid sediments of several hundred meters thick, and that the claim of the origin of any ethnic group from its banks is at best a predilict speculation. If the surveys are conducted, such subterranean river beds can be found all-over India.

..... energetic minister of culture [Republic of India] deployed considerable resources of government (to go by his press statements) is breath-taking; there have been, says, BP Radhakrishna, such “tectonic disturbances” after 5000 BC as cut off the Sarasvati “from the perennial source of water from the snowy Himalayas” (pp.8-9). For this he surprisingly cites not a geologist but OP Bharadwaj, with no known geological skills. Bharadwaj puts this “large-scale tectonic-seismic-volcanic upheaval” (p.190) even later, around 3000 BC. Uptill now no proof has been offered of such recent volcanic activity in the Himalayas within the Holocene, and Bhardwaj’s reference to it should surely have put Radhakrishnan on guard. As to “seismic” there is no known earthquake in history which could have had such consequences as levelling huge high mountains and raising others to divert courses of rivers in the Himalayan range. Not a single instance of an earthquake-induced change of course in a mountain river of this magnitude has been cited anywhere.

Finally, “tectonic”: it is so convenient a word these days! But let us see what work we are going to demand from the tectonic uplift. As our contours show, the Sarasvati is separated from the “snowy” Himalayas by the Shiwaliks which rise to 1500 ft. and then by the lower Himalayas which rise to well over 2000 ft. The only way the Yamuna could have captured any Himalayan source away from the Sarasvati is to have diverted Giri river which flows almost due east into the Yamuna from an earlier supposed connection with the Sarasvati. But Giri is separated from the present source of the Sarasvati (reaching barely to a level of 1,000 ft.) by a Lower Himalayan range nowhere below 2000 ft. and with a peak rising to 5030 ft. In order to imagine that the Sarasvati could have had a connection with Giri river at any time we must imagine an intervening tectonic uplift of at least 1000 ft. or above 300 metres, which alone could have broken this connection.

The beginning of the rise of the Himalayas is dated back to Eocene, or, let us say, some 50 million years ago. If they rose 10,000 metres (which is above the height of Mt. Everest), they have risen, on average just one metre in 5000 years! Even if one brings down the period of the rise of the Himalayas to 25 million years ago (Miocene) it would be an average rise of one metre in 2500 years. A tectonic rise of 300 metres over such a large area as one is being asked to imagine in 2000 years (average: one metre in seven years) would not only have shaken up the Himalayas, it would have rocked the entire globe with unimaginable consequences (including earthquakes). And all this just to have had Giri river flowing into Sarasvati, a situation in which Sarasvati would have been a somewhat larger, but still not a “great”, river.

If such is the case with the presumed previous connection with Giri river, a rather modest Himalayan stream, we can see that any connection with the Sultej or any of its Himalayan tributaries on its left side would be even more impossible: a tectonic lift of some 600 metres might be required at the very least. We would practically have to say that the Himalayan ranges below Shimla were all created after 5000 BC!

So much for the Himalayan sources of the Sarasvati. The other assertion is that both the Yamuna and the Sutlej were tributaries of the Sarasvati in the plains. We must now remind ourselves again that we have to confine ourselves to the Holocene. There are all kinds of palaeo channels which LANDSAT imagery throws up, of which two good maps one of the whole Indus basin and the second of the Bahawalpur-Rajasthan area are provided in the Vedic Sarasvati volume, at pages 241-2. The basic fact is that there is not the slightest trace in LANDSAT imagery of any palaeo water-course beyond the point in Bahawalpur where the Ghaggar-Hakra (“Ghaggar/Sarasvati/Markanda”) river’s dry channel today disappears, so that there is no evidence connecting the dead river either with the Indus or to Eastern Nara. In other words, the Ghaggar system rivers have never carried any volume of water at any time that could have made the Ghaggar a tributary of the Indus or the Eastern Nara. The existence of a Sarasvati of immense proportions is thus disproved by LANDSAT imagery.

A possibility certainly exists of a channel leaving the Yamuna – one can see how one Yamuna channel below Khizrabad runs in the direction of Chautang R. On the other hand there is also a Sarasvati channel that leaves it above Thanesar to join the Chautang. The Chautang follows a long course south and then west, past Hansi and Hissar running dry around Bhadra, below what its dry bed runs into that of Ghaggar. Such a connection of Yamuna with Chautang, and Sarasvati as a tributary of Chautang is, indeed, topographically possible. Yet how this connection could convert that river into Sarasvati is difficult to imagine, since, then, Sarasvati would only be a petty tributary of a Yamuna flowing eastward.

In another major finding, the researchers believe they have settled a long controversy about the fate of a mythical river, the Sarasvati. The Vedas, ancient Indian scriptures composed in Sanskrit over 3000 years ago, describe the region west of the Ganges as “the land of seven rivers.” Easily recognizable are the Indus and its current tributaries, but the Sarasvati, portrayed as “surpassing in majesty and might all other waters” and “pure in her course from mountains to the ocean,” was lost. Based on scriptural descriptions, it was believed that the Sarasvati was fed by perennial glaciers in the Himalayas. Today, the Ghaggar, an intermittent river that flows only during strong monsoons and dissipates into the desert along the dried course of Hakra valley, is thought to best approximate the location of the mythic Sarasvati, but its Himalayan origin and whether it was active during Vedic times remain controversial.

Archaeological evidence supports the Ghaggar-Hakra as the location of intensive settlement during Harappan times. The new geological evidence—sediments topography— shows that rivers were indeed sizable and highly active in this region, but most likely due to strong monsoons. However, there is no evidence of wide incised valleys like along the Indus and its tributaries and researchers did not find any cut-through, incised connections to either of the two nearby Himalayan-fed rivers of Sutlej and Yamuna. The new study argues that these crucial differences prove that the Sarasvati (Ghaggar-Hakra) was not Himalayan-fed, but a perennial monsoon-supported watercourse, and that aridification reduced it to short seasonal flows.

Our provenance studies now allow some important constraints to be placed on reconstruction of the river systems since the mid Holocene. Our data show that the Yamuna likely flowed west, not east as it does now, at least prior to 49 ka. Such a change in drainage pattern is possible because the Yamuna reaches the Himalayan foreland close to the crest of the drainage divide. Why the switch from Indus to Ganges occurred is unknown but could reflect a number of processes diverting the river east, such as an avulsion event driven by autocyclic processes, as seen for example by the 120 km shift of the Kosi River in 2008. The Beas River was delivering material directly to Tilwalla prior to 10 ka, which in turn would require the Sutlej to have flowed into the Ghaggar-Hakra east of Marot. This means the northern Thar region must have been an area with several major confluences and a large river with a combined flow arguably sufficient to reach as far as the Arabian Sea. While drainage from the Yamuna may have been lost from the Ghaggar-Hakra well before development of the Harappan Civilization, flow from the Beas and Sutlej may have been more recent in Cholistan, if still prior to 10 ka. Loss of these rivers might be expected to have had a catastrophic effect on sustaining settlement in this region, but our evidence argues against this. Water in the small Ghaggar-Hakra (or Sarasvati) River would have been further reduced by monsoon weakening from 4.2 ka (Enzel et al., 1999; Staubwasser et al., 2003; Wünnemann et al., 2010), but evidence for dra- matic changes in water sources was much earlier. While drainage capture is dramatic in the eastern Indus Basin in the late Quaternary, it appears to have occurred prior to human settlement and not to have directly caused the Harappan collapse.

We have tried to examine the hypothesis from the view point of chronology of flood plains and sand dunes distributed along the Ghaggar River. First we compared the size of present flood plain of large rivers originated in glacial area with that of the Ghaggar, and got to know that the size of flood plain became wider in proportion to the volume of annual river flows. It means that present size of flood plain of the Ghaggar can be formed by present volume of annual river flow. Next we measured the oldest age of sand dunes limiting the size of present flood plain by using OSL dating method. Finally we resulted that the Ghaggar was not the mighty Saraswati during mature Harappan period because sand dunes on either side of the Ghaggar had been formed before that.